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SUP2.1KNOWLEDGETRANSFER

DATAMODELING

MICHAEL HO

OCTOBER 20, 2011

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2CompanyConfidenalDecember12,2011

CONTENTS

MBODefinion DataLoading CachePolicies DataModelImplicaonsonClient ChallengesintheField SUP2.1.1Preview

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3CompanyConfidenalDecember12,2011

MBODEFINITION

THEMBODATAMODELISTHECLIENTDATAMODEL

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4CompanyConfidenalDecember12,2011

MBODATAMODEL

MBOdatamodelisNOTamodelforbackendbusinessobjects ItisthedatamodelforthemobileapplicaononthedeviceAuserreplicatesthedatamodelforthedesktopapplicaon

onthedevicewheremanyoftheaributesareneverused,

leadingtoslowsynchronizaonandperformancedegradaon

EmpiricaldatashowsthatMBOdatamodelimpactsnotonlymobileapplicaondevelopmentbutsynchronizaon

performance

MBOdefinionshouldtakeintoconsideraonmobiledatabaselimitaons

Synchronizaongroupdefineswhattosynchronize CachegroupdefineswhatandwhentoloadfrombackendtofillthetablesinCDB

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MBODATAMODEL

Relaonshipenablesnavigaon,whole-partremoval,cascadeoperaons

Supportsassociaon(itemsproduct)andcomposion(salesorderitems)

SurrogatekeyschemeontheclientdatabaseAsprimarykeyforsynchronizaonForeignkeytoimplementrelaonship

Cacheassociatessurrogatekeywithbackendprimarykey

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MBODATAMODEL

Backendcreateoperaonexpectedtoreturnprimarykeysoassociaonbetweensurrogatekeyandprimarykeycanbeformed

Synchronizaonparametersserveassubscripontodownloaddata

CanhavemulplesetsofsynchronizaonparametersatanygivenmeDatacorrespondingtothesesetsofsynchronizaon

parametersaredownloadedtothedevice

Maydeleteen#recolleconofsynchronizaonparameterssetstoreclaimstoragespace

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GOODMBOMODELINGPRACTICEMBODEFINITION EveryaUributeisusedbythemobileapplicaon MBOinstance=databaserow(mustfitwithinapage)Largerowsizerequireslargerpagesizeimpacng

performanceondeviceandsynchronizaon

DonotdefineaMBOwithmorethan50aributesDonotuseSTRINGdatatype.Instead,useSTRING(n)to

definethemaximumstringlength(STRINGdefaultsto300)

PromoonofVARCHAR(n)toLONGVARCHARcanoccurduringcodegeneraonifthespecifiedpagesizeislessthan

thecalculatedmaximumrowsizeUselargerpagesizeduringcodegeneraonandrunwitha

smalleroneondeviceifnormalsizeismuchlowerthan

maximum

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GOODMBOMODELINGPRACTICEINDEX setheminimumnumberofindexestosupportqueriesusedbythemobileapplicaon

Indexslowsdownupdateoperaonsondeviceandsynchronizaon,especiallyonlowenddevices

UncheckfindByPrimaryKeyandFindAllqueriesgeneratedforeachMBObydefaultiftheyarenotneededbythemobileapplicaon

Determineifindexshouldbecreatedforuserdefinedobjectqueries

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GOODMBOMODELINGPRACTICESYNCHRONIZATIONGROP sesynchronizaongrouptoaddflexibilityonwhattosynchronize

ControlswhichMBOstosynchronizeataparcularmeSupportspriorizaoni.e.getservicecketswithoutdetailsLimitstheamountofdataduringsynchronizaonfor

customersfacingimpairedconnecvitytoavoidrepeatedlytryingtocompletealargesynchronizaon

Thinktwiceifthesynchronizaongrouphasmorethan5members

Runmeflexibilityavailablebycombiningsynchronizaongrouptoreduceoverhead

Relaonshipacrosssynchronizaongroupsmayresultinincompleteobjectgraphsontheclient

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GOODMBOMODELINGPRACTICECACHEGROP secachegrouptocontrolwhatandwhentoloaddataintoCDB

BreakupexpensivedataretrievalsfrombackendRelaonshipacrosscachegroupmayresultinincomplete

objectgraphsinCDB

Mappingcachegrouptosynchronizaongroupreducesunnecessaryrefreshnotrelatedtothetriggering

synchronizaon

Avoidcirculardependenciesbetweencachegroups.Similarly,avoiddrivingtheloadofanMBOinonecache

groupbasedontheaributesofanMBOinanothercache

group

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GOODMBOMODELINGPRACTICEPRIMARYKEY MBOprimarykeyshouldmatchbackendbusinesskey MBOwithacompositeprimarykeyandtheEISloadoperaonparametersdonotmatchinscope,datamaybe

duplicatedinthecache

Ifnoprimarykeyismodeled,animplicitcompositeprimarykeythatismadeupofallcolumnsisgenerated

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GOODMBOMODELINGPRACTICESYNCHRONIZATIONPARAMETER Synchronizaonparametersshouldbedefinedandmappedtoallresult-affecngloadparameters

MBOusesWSoperaongetAllBooksByAuthor(Author,userKey)whereuserKeyissimplyamechanismtoauthencateauser

anddoesnoteffecttheresultsoftheoperaon.Inthiscase

"userKey"isnotaresult-affecngparameterandthereforeshouldnotbemappedtoasynchronizaonparameter

MBOusesWSoperaongetEmployees(Group,department).Groupismappedtoasynchronizaonparameterbutdepartmentis

mappedtoapersonalizaonkey.Theparonidenfiedby

Groupisnowconstantlyoverwrien

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GOODMBOMODELINGPRACTICEPARTITION Paronisparons/uniqueEISresultsetsidenfiedbytheresultaffec+ngloadparameters

semulpleparonswheneverpossible.Bydefault,wehaveasingleparon

Increaseparallelism Loadvs.load,loadvs.update

ReducerefreshlatencyData/rowsmustnotbecontainedinmulpleparon

otherwisedataneedtobeconstantlyupdated,evenifthe

actualbusinessdatadidn'tchange,asitwillbouncebetweenparonsandthatseverelyimpactsperformanceand

downloadincorrectdatatoclient

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GOODMBOMODELINGPRACTICEPARTITIONParonscanalsobeusedtogetdata"real-#me"whenusing

acacheintervalofzeroandverysmallparonsintheirowncachegroup/syncgrouprelaonship

Parongranularity Toocoarse-longrefreshmeToofinehighoverheadduetoEIS/SUPchaness.Itismoreefficienttohavereasonablychunkyinterfacebetweenservernetworked

components

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GOODMBOMODELINGPRACTICESHAREDREADMBO sesharedreadMBOwhenappropriatePopulatemulpleMBOswithasingledataretrieval

invocaonforefficientdataloading

AllMBOssharethesameparonkey, theywillalwaysbeloaded/refreshedtogetherwhenthecacheexpired

ApplyoperaonsresultsalwaysonlyappliestotheMBOinstancetheoperaonisexecutedon,youcannotfill

mulpleMBOfromasingleoperaonoutput/result*

ForApplyResultstoCachetowork,theoutputfromoperaonhastolookjustliketheoutputfromtheprimaryread*

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GOODMBOMODELINGPRACTICESHAREDREADMBOSharedreadisveryusefultoreadobjectsintothecache

efficientlyandtransaconally,yousllhavetouseclientparametersfortransaconalwriteoperaons*

ChildrowscannotbeapplytocacheAlternavely,useMLItochaindiscretecreaonoperaons

withinthehierarchy

Rootcreateoperaonreturnsprimarykeyforassociaonwithsurrogatekeyandchildcreaon

Applyresultsshouldbeusedwheneverpossible,ifonewantstomaintainthesurrogate->businesskeyaffinity

Invalidatecacheisrequiredtobeusedifthedevicesidecontentmustbeconfirmedinthemostmelyfashion

Mulpleparonstoreduceinvalidate-refreshcosttoretrieveresult

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DATALOADING

FILLINGTHECDBWITHENTERPRISEDATA

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DATALOADINGDESIGNPREPARATION

KnowThyDataReferencevs.Transaconal:MostlyReadvs.Read/WriteSharedvs.PrivateSourcesofchanges:coherencyimplicaonsUpdatefrequencyandfreshnessrequirementAccesspaern:peakandvalleyordistributedDatavolume:sizedoesmaer

KnowThyDataSourcesEfficiencyofinterface

Protocol:JCOvs.WebServices API:Numberofinvocaonsrequired

Pushvs.Pull

Reacontopeakload

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RLEOFTHMBRE:DATALOADING

DonotuseexisngAPIjustbecauseitisthereEvaluateitsefficiencyforloadingdataintoCDBDevelopcustommobileadaponifappropriateLoadwhatisneedednotwhatisprovided

seanefficientinterface(protocol)forhighdatavolume seDCNforverylargedatavolumeAvoidslargedatatransferanddifferenalcalculaonDoesnothelpwithinialloading

semulpleparonstosplittheloadingwheneverpossiblePrivatedatashouldconsidertheuseofparonby

requesteranddeviceidentyorequivalent

DevelopbackendAPItoloadbyparonifappropriate

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RLEOFTHMBRE:DATALOADING

DonotmixDCNwithscheduledorondemand DonotuseverylargeDCNmessagetoimproveefficiencyExcessivememoryconsumpontoprocesslargemessageMayblockdownloadduetomanylockedrows

secachegroupstogroupMBOswithsimilarusagecharacteriscstotuneloadperformance

Referencevs.transaconalPrivatevs.shared

sesharedreadoperaonsifpossibleReducebackendinteracons

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REFERENCEDATA

[MostlyRead,LargeDataVolume,LowVolality] Strategy:CacheandShare OnDemandwithnonzerocacheintervalAlleviatelargeinialdataloadingissuethroughparoningif

userstakedifferentsubsetsofthereferencedata

Largeinialloadisspreadoutoverme Loaddataondemandandinparallel

Sasfydatafreshnessrequirementthroughcacheinterval

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REFERENCEDATA

ScheduledMatchbackendwithpredeterminedreferencedataupdate

schedulee.g.batchrun@midnight

ParoningtorestrictloadingonlyforsubscribeddataNotrecommendedforhighdatafreshnessifbackenddatais

volaleaswearelimitedbytheupdateinterval

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REFERENCEDATA

DCN(FillandFilterModel)Enablebackenddatachangepropagaontocachewith

lowestcostcomparedtoondemandorscheduled

EnablesSISwithoutextraworkSupportshighdatafreshnessthroughproperchange

deteconinterval

cacheintervalUsesynchronizaonparametersforfilteringdownloaddataHighinialloadcostforlargedatavolumecanbeanissue

SERVER INITIATED SYNCHRONIZATION

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SERVERINITIATEDSYNCHRONIZATIONREFERENCEDATA OnDemandChangedeteconfunconalifsomeonerefreshedthedata+

cacheexpiraon(NZCI)

ScheduledChangedeteconfunconalwheneverthechangeispulled

intothesystem DCNMostopmalwithSISaschangesarepushedtothecacheChangedeteconfunconalaerpush

NoficaonMBOpaUernforOnDemandwithZCI

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READ/WRITEDATAWITHCACHEINTERVAL

DataincacheusingNonZeroCacheIntervalSystemofRecord

Ithelpstoreducenumberdataretrievalinvocaonstobackend

Applyresultstocacheisnotalwaysthesameaswhatisinthebackendevenwhentheoperaonsucceeds

Racecondioncanproduceastaleresultinthecacheunlnextrefresh.IncaseofDCN,itmaybeunlthenextupdate

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TRANSACTIONALDATA(PRIVATE)

[Read/Write,PerserData,LowVolume,ModerateVolality] OnDemandwithzerocacheintervalDataisalwaysconsistentwithbackendRequester/Devicebasedorequivalentparoninglimits

refreshcost

SIScanbeimplementedthroughnoficaonMBOpaernEvaluateifbackendcanhandlepeakloadifuserstendto

synchronizewithincertainmeoftheday

OnDemandwithnonzerocacheintervalNobenefitunlessusersynchronizesrepeatedlyinsuccession

e.g.submingoperaonanddownloadingofappliedresults

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TRANSACTIONALDATA(PRIVATE)

ScheduledEnablesSISbasedoncacheintervalPerformanceimplicaons

DCNEnablesSISwithoutextraworkSupportshighdatafreshnessthroughproperchange

deteconinterval

Dataisnotalwaysconsistentwithbackend.Mayrequireanotherupdatetofixtheinconsistency

Seenotes

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TRANSACTIONALDATA(SHARED)

SharingattwolevelsMBOinstanceslevel(ML)Paronlevel(PL)

OnDemandwithnonzerocacheintervalSISbasedonusersynchronizaonacvity+expiraonParonbyRequesterandDeviceIdenty(ML)

Duplicatedrowsinnon-overlappingparons Duplicatedparonsifuserhasmulpledevices

Paronbyuserspecificidenty(ML) MakesurethattheuserspecificidentyiscombinedwithbackendprimarykeytoformtheMBOprimarykeytoavoidsharedrowbouncing

betweenparons

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CACHEPOLICY

STAGINGVS.CACHING

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CACHEPOLICY:ONDEMAND

Refreshtriggeredbysynchronizaon ZerocacheintervalAllowslatestdatafrombackendtoberetrievedUnlessdatavolumeissmall,shouldbecoupledwithparoningUsersynchronizaonacviesallowchangestobedetected

NonzerocacheintervalReducedataloadinginvocaonsagainstbackendCoupledwithparoningtoreduceamountofdatatobeloaded

perinvocaon

Usersynchronizaonacvies+cacheintervalexpiraonallowchangestobedetected

ChancesofinconsistencywithbackendIncreaseparallelismwhenforshareddata

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CACHEPOLICY:ONDEMAND

Refreshtriggeredbysynchronizaon ZerocacheintervalAllowslatestdatafrombackendtoberetrievedUnlessdatavolumeissmall,shouldbecoupledwith

paroning

Usersynchronizaonacviesallowchangestobedetected

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CACHEPOLICY:SCHEDLED

Automacrefreshbasedoninterval Cacheintervalisbasecasenoficaongranularity Paroninghelpstospreadoutinialdataloading Matchbackenddataupdatefrequencyespeciallyforreferencedata

Chancesofinconsistencywithbackend

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CACHEPOLICY:DCN

Singleparon Downloadfilteringviasynchronizaonparameters Inialdataloadingcantakealongme.Synchronizaonmustwaitforloadingtocomplete

Concurrencywithsynchronizaon@rowlevel DCNtakesadvantageofmulpleSPserversintheclustertoparallelizeloading

seanoficaonMBOtoletdeviceknowdataisready ReferredtoMBOshavetobepushedbeforereferringMBOs

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DATAMODELIMPLICATIONSONCLIENT

LIMITATIONSOFMOBILEDATABASE

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CLIENTIMPLICATIONS

DatabasepagesizegovernedbymaximumrowsizederivedfromMBOdefinion

Lotsofaributesorlengthyoneslargerrowslargerpagesize

OnsomedevicesliketheBlackberry,morethanmemoryisconsumedobjecthandles

Basedonourobservaons,pagesizesbetween1k4kseemstoprovidebestoverallperformance

DonotforgettoaccountfornonLanencodingwhichwillresultinlargerowsize

Largerowsmeanslessrowsperpageandmorepagesmustbefetchedorcached.ForMBOsusedinlistviews,thiscan

impacttheUIresponse

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CLIENTIMPLICATIONS

LargeMBOinstanceleadstoslowandexpensiveobjectinstanaon

Objectqueryreturnsobject(s)anddynamicqueryreturnsresultset.sedynamicquerytobypassobjectinstanaon

andselecvelyretrieveasubsetofaUributes

Forone

manyoronemanyrelaonshipwherecount(many)islarge

Navigaonandcascadeoperaoncanbeexpensive Doesthedatamodelenableapplicaontousesimplequeriesformostusecases?

Simplejoinsareexpensiveonmobiledevices.ThisistrueevenforiPhoneandthelike

Indexesslowdownsynchronizaonandupdates

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